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Flexible Injection is a new processing technique for the manufacture of advanced composites made of continuous reinforcing fibers and thermosetting polymer matrix. The primary objective of this new process is to provide faster and less expensive manufacturing than traditional methods like autoclave processing or Resin Transfer Molding. The present paper investigates the effectiveness of the proposed method to produce composite structures possessing sharp corners. A specially devised setup is used to manufacture out of glass fibers and vinyl ester resin a series of Z-shaped parts with small radii. The quality of the fabricated parts is assessed to detect possible defects induced by the manufacturing process. Each stage of the production cycle is analyzed thoroughly to develop a simplified finite element model reproducing the fiber bed behavior during processing. Parametric studies are conducted to evaluate the impact of processing conditions on the quality of final products. The combination of numerical simulations and experimental observations demonstrates clearly the importance of the preforming stage. At the same time, it provides useful insights on the physical phenomena occurring during Flexible Injection. [ABSTRACT FROM AUTHOR]

In vacuum infusion processes fiber preforms are placed onto the single molding surface and enveloped with a non-rigid polymer bag which is sealed to the molding surface. The flexible bagging film does deform during the resin infusion process thus changing the compaction of the fabric. However, one can also relax the preform by drawing a partial vacuum in a rigid chamber placed on top of the flexible bag which will increase the permeability of the fabric under the chamber. A numerical model is presented to characterize the change in permeability and describe the mold filling for such processes in which the fabrics undergo controlled relaxation by external stimuli. The predictions from the simplified model agreed reasonably well with the experiments. This characterization and resin flow front prediction with time method should prove useful in processes such as Vacuum Induced Preform Relaxation (VIPR) process which can be used to actively manipulate flow in a vacuum infusion process. [ABSTRACT FROM AUTHOR]